Dryer for heating and removing moisture for aggregate material



May,17, 1966 E. H. FRAENZEL 3,251,140

DRYER FOR HEATING AND REMOVING MOISTURE FOR AGGREGATE MATERIAL Filed June 5, 1963 3 Sheets-Sheet l FlG.l.

INVENTOR E. H. Froenzel BY yMfM ATTORNEY May. l7, 1966 E. H. FRAENZEL 3,251,140

DRYER FOR HEAT AND REMOVING MOISTURE FOR AG GATE MATERIAL 3 Sheets-Sheet 2 Filed June 3, 1963 Fl 6.2. INVENTOR E. H. Fruenzel %J ATTORNEY E. H- FRAENZEL 3,251,140 DRYER FOR HEATING AND REMOVING MOISTURE FOR AGGREGATE MATERIAL May,v 1 7, 1966 3 Sheets-Sheet 5 Filed June 5, 1963 FIG.3

INVENTOR E. H. Frclenzel M ATTORNEY United States Patent 3,251,140 DRYER FOR HEATING AND REMOVING MOIS.

TURE FOR AGGREGATE MATERIAL Edward H. Fraenzel, Danville, Va. (Rte. 2, Forest, Va. 24551) Filed June 3, 1963, Ser. No. 284,877 Claims. (Cl. 34-137) The present invention relates to improvements in asphalt plants, and more particularly to a dryer for removing moisture from the aggregate material such as stone and sand as well as other aggregate types.

One object is to provide a dryer having an enlarged intake breaching to reduce the air velocity at the intake end of the retort to prevent particles of aggregate from being carried through the stack end of the retort and eliminate excessive loss of the smaller particles of aggregate material.

Another object is to provide an intake breach with a stack portion extending obliquely upwardly and designed to produce a dust and particle pathway in which the larger particles will be thrown and projected by centrifugal force and will then return by gravity to the lower portion of the retort and will be mingled with the material to be dried as it passes into the charging end of the retort.

Another object is to provide a rotary dryer retort in which the aggregate to be treated is fed by an endless conveyor to the charging end of the retort with the conveyor discharge located adjacent the lower portion of the retort to prevent the material from collecting in piles and creating excessive wear at one end of the rotary retort. 1

Another object is to provide a conveyor feed which can be operated at a relatively fast rate of speed to project the material being treated a considerable distance into the retort to prevent piling and bunching at the charging end and to increase the capacity without increasing the dimensions of the retort.

' Another object is to provide sealing means for sealing the material to be treated as it enters the charging end of the retort and to seal the interior of the retort against entrance of air in the Zone immediately above the charging area.

Another object is to provide a charging conveyor associated with the breaching end of the conveyor support and at the lower portion of the retort in which a pair of head rollers are employed arranged in spaced parallel relation to prevent wet aggregate material from clogging at the entrance zone and eliminate excessive wear therein.

Another object is to provide a conveyor feed for a retort dryer in which the discharge end is located a considerable distance below the diametral point of the retort when said point is considered extending in a horizontal direction to eliminate the use of lengthy endless conveyors and to also eliminate the use of highly elevated feed bins.

Another object is to provide a scraper for removing the material to be dried from the endless conveyor belt and to provide guide means' for directing the material into the retort so that the wet material will not pile even though the conveyor is operated at speeds greater than conventional feeding conveyors. The guide means also eliminates excessive retort wear since the material enters the lower portion of the retort without falling by gravity and without causing the aggregate particles to strike the internal surface of the retort with excessive force.

Another object is to provide a stack connection with the centrifugal separator of the plant in which the larger particules of aggregate material will be returned to the material entering the retort and will not cause excessive wear to the ducts entering the centrifugal separator and thus eliminate frequent replacement and repair of the various parts thereof.

of the retort.

FIGURE 2 is an enlarged fragmentary vertical crosssectional view through the breaching end of the retort showing the manner in which the endless conveyor is arranged to discharge material to be dried therein and also illustrating the gas flow path and the direction of travel of heavier particles which are returned to the material entering the retort.

FIGURE 3 is an enlarged fragmentary view partly in section illustrating the breaching end of the retort in end elevation and showing the manner in which the charging opening is sealed by an adjustable entrance restricting plate, and

FIGURE 4 is an enlarged fragmentary cross-sectional view taken on line 44 of FIGURE 3 and looking in the direction of the arrows to illustrate the manner in which the endless conveyor is supported adjacent the lower portion of the rotary retort so that the material to be treated will be projected therein.

In the drawings, and more in detail, attention is directed to FIGURE 1 wherein there is shown a rotary retort dryer for an asphalt plant including a rotary retort 6 generally designated, a heater generally designated 7 and acharging conveyor generally designated 8. A centrifugal separator generally designated 9 is associated with the breaching end of the retort 6 by means of an enlarged upwardly and obliquely extending centrifugal separating member 10.

The dryer assembly is supported on a rectangular frame structure 12 mounted'on suitable jacks 13, 14 and 15 to permit the frame structure to be tilted to any desired angular position. Mounted on the frame structure and on each side thereof is a pair of supporting rollers 16 mounted in spaced bearing supports 17. Similarly, a pair of rollers 18 are mounted adjacent the other end of the frame 12 and are rotatably supported by upstanding bearing brackets 19. The retort 6 is of cylindrical shape and includes an elongated cylinder 20 having spaced apart roller engaging tracks 21 and 22 secured thereto by welding or the like. The track 21 is supported by the rollers 16, while the track 22 is rotatably supported by a pair of spaced rollers 18.

Also secured to the cylindrical retort 20 is a gear track 23 which is adapted to be driven by a gear wheel 24 having its axis shaft 25 journaled in bearing brackets 26. An electric motor 27 has its armature shaft drivingly con nected to the shaft 25 by means of a suitable speed re ducer and coupling 28 energization of said electric motor from a suitable source of electrical energy the retort 6 will be rotated on the tracks or tires 21 and 22.

A discharge duct 30 encircles one end of the retort 6 i and has a branch portion-31 to discharge the dried material for further treatment. Secured to the circular duct 30 is a combustion chamber 31' supported on the frame 12 by means of a supporting bracket 32.

The heating means 7 includes a high velocity oil burner having a heat shield 34 and said high velocity oil burner projects a flame through the combustion chamber 31' and into the retort 6 for a considerable distance. The high velocity oil burner 33 is the subject matter of my United States patent application SerialNo. 278,024 filed May 6, 1963, and is co-pending herewith.

The internal surface of the retort is provided with a series of longitudinally extending circumferentially spaced flight bars 35 to tumble the material while it is being 3 treated (FIGURE 2), and the opposite end is provided with an inwardly extending annular flange 36.

Returning to FIGURE 1 the centrifugal separator 9 is of the vortical type and includes a collection chamber 37 having a frontal shaped hopper portion 38 with its outletend connected to a duct 39 leading to and connected with the discharge duct 31. A centrifugal whirl chamber 40 is provided with an inlet duct 41 arranged tangentially with respect to the whirl chamber 40 and the upper end of said chamber is connected to a duct head 42 to which is connected a duct 43 with its other end connected to the inlet of a blower 44. The outlet of the blower is connected to a vertical stack 45 exhausting to the atmosphere. The blower 44 is provided with a rotor shaft 46 supported on suitable brackets 47 and an electric motor 48 has its armature shaft provided with a pulley which is drivingly connected to a similar pulley on the shaft 46 by means of a drive belt 50.

The end of the retort opposite the burner is open and is adapted to be closed by the upwardly and obliquely extending centrifugal separating member which is in the form of a gas ofitake housing having an intake breaching (FIG. 3). The gas otftake housing is provided with an annular flange 52 which fits within the opening formed by the inwardly extending flange 36 as at 53. The housing comprises plate-like wall portions 54 which extend obliquely upward in spaced apart relation and said wall portions terminate at their upper ends in vertical wall portions 55 which extend angularly to the oblique portions 54 and said vertical wall portions 55 are shaped to provide vertical side walls 56 of a horizontal ofltake duct or housing.

The plate-like wall portions 54 of the housing 10 are supported by vertical uprights 57 the lower ends of which are secured to the frame structure 12 as at 57, while the upper ends of said uprights are connected to the side plate-like portions 54 by suitable fasteners as at 59. The curved lower edges of the side plate-like wall portions 54 are welded to the annular flange 52 and form a wall portion 65.

Extending upwardly and obliquely from the annular rim 52 is a wall 60 which merges as at 61 with a vertical wall portion 62. The wall 62 is curved as at 63 and extends horizontally as at 64 to form the bottom wall of the duct leading to the centrifugal separator 9. The walls 60, 62, 63 and 64 are welded or otherwise secured to the side plates or walls plate-like wall-portions 54,55 and 56. The intake wall 65 extends in a direction inclined and upwardly from the lower portion of the annular flange 52 and has its longitudinal edges welded or otherwise secured to the lower oblique portion of the plate-like wall portions 54. The inclined wall 65 terminates as at 66 and continues upwardly in a vertical wall portion 67 which is welded or otherwise secured to the vertical edges of the vertical portions 55 of the plate-like Wall portions side plates 54. The vertical wall portion 67 terminates in a corner area 68 and is connected to a horizontal wall portion 69 which connects the upper edges of the vertical wall portions 55 and their extensions 56. The horizontal top wall 69 is likewise welded or otherwise afiixed to the horizontal edges of the vertical portions 55 and horizontal portions '56, thus forming a closed duct which merges with the inlet duct 41 and may be connected thereto by means of a suitable coupling as at 70. Thus, a relatively sharp corner is formed at the upper portion of the duct in a plane in substantial alignment with the inclined wall 60, and the curved portion 63 at the point where the walls 62 and 64 merge is arcuately curved.

The conveyor 8 is adapted to feed aggregate material to the charging end of the retort and includes a pair of longitudinally extending spaced apart frame bars 71 held in place by suitable transverse bars (not shown). Journaled between the lower ends of the frame bars 71 is a conveyor roller 72, while mounted between the upper ends of the frame bars 71 is a pair of spaced head rollers 73.

A flexible endless conveyor belt 74 is trained over the rollers 72 and 73 and a series of supporting rollers 75 are rotatably journaled between the side frame bars 71 for supporting the flexible conveyor belt 74 to form a troughshaped surface. A guide roller 76 is also journaled between the side rails 71 and the side plates 78 which extend through the opening 79 formed in the lower portion in the inclined housing wall 65 with their nose portions 89a projecting therethrough and resting upon the annular flange 52.

A motor 80 is supported on the lower portions of the frame bars 71 and is provided with a pulley 81 drivingly connected to a gear box 83 by means of a drive belt 84 which is trained over the pulley 85 on the drive side of the gear box. Thus, the pulley 82 drives the conveyor belt 74 and a hopper 86 is provided for feeding material deposited therein to the belt.

Formed on each of the side plates 78 at the lower portion thereof is an extension 90 forming supporting feet which rest upon the annular flange 52. Each bracket is provided with extensions 92 between which is mounted a pin 93. Pivotally mounted on the pin 93 is a plate 95 by means of spaced bearing lugs 96. The plate 95 is provided with upstanding arms 97 at the ends thereof and coil springs 98 have one end attached to the upper ends of the arms 97 as at 100, while their other ends are hooked and are received in openings 101 in the nose portions 80a of the side plates 78.

In FIGURE 4 the side plates 78 are shown as being bolted as at 102 to the side frame bars 71 of the conveyor and the rollers 73 are supported by suitable journal bearings 103 and 104, the former being attached to one of the cross bars 105 connecting the side frame bars 71, while the latter is supported by spaced angle brackets 106 suitably fastened in place to a flanged portion of the bars 71 by threaded fasteners or the like.

Formed in the lower portion of the inclined Wall 65 of the intake duct 10 is the opening 79 through which the upper inclined end of the conveyor projects so that material to be treated will be fed therethrough and discharged into the rotary retort 20, and said material is scraped or removed from the conveyor by means of a doctor blade 107 which is yieldingly urged into engagement with the endless conveyor belt 74 by means of the springs 98. Also extending between the extensions 90 of the nose 80a is a plate 108 to seal the lower portion of the conveyor belt and prevent the entrance of air to the interior of the retort.

The entrance openings 79 in the inclined Wall 65 is sealed at the sides by adjustable plates 109 the upper ends of which are longitudinally slotted as 'at 110 and are adjustably secured in place by threaded fasteners 111. An adjustable central sealing plate 112 is provided with a series of parallel slots 113 which receive adjusting screws 114 to permit the sealing plate 112 .to be adjusted to any desired position below the upper edge 79 of the opening. The lower edges of the sealing plates 109 and 112 are provided with rubber sealing strips 115 and 116 and the sealing strip 116 is provided with a lower curved edge to conform to the shape of the material A (FIG- URE 3) being charged into the retort on the surface of the endless conveyor belt 74. I

The sealing plate 112 can be adjusted by means of an adjusting screw 118 (FIGURES 3 and 4) which has one end secured to an angle bracket 119 at the upper end of the sealing plate 112 with its other end extending through an adjusting plate 120 welded or otherwise affixed to the inclined surface or plate 65 of the otftake housing or discharge duct 10. Nuts or other threaded fasteners 121 and 122 are threaded on the screw 118 and are arranged on opposite sides of the adjusting plate 120. Thus, by adjusting the nuts 121 and 122 on the screw or threaded shaft 118 the adjustable plate 112 can be moved to various positions of adjustment and retained in fixed relation by the nuts 121 and 122 as well as the threaded fasteners 114.

. It is noted that the lower portion of the plate 112 has its edge angulanly cut and that the sealing strip 116 is curve-d along is lower edge to conform to the material A on the conveyor 74. Also, the rubber strips 115 have their lower edges stepped to provide a cutaway portion 130 to conform to the edge portion of the endless conveyor belt 74 and at the same time engage the end peripheral surfaces of the upper head roller 73. Thus, the opening 79 is effectively sealed against the entrance of air to the interior of the dryer when the same is in operation and when the upper end of the endless conveyor 8 is presented to the lower portion of the housing so as to project through the opening 79 and be supported by resting on the rim 52 on the lower edge of the opening 79 as at 131 (FIGURE 4).

The duct or housing generally designated 10 is shaped so that the wall portions 54, 60 and 65 will form an obliquely and upwardly extending duct of the housing 10 while the walls 55, 62 and 67 form a vertical duct portion of the housing 10 which terminates at the upper end in horizontal and vertical wall portions 6469 and 56 to form a horizontal duct portion of said housing 10. In order to provide a substantially circuitous pathway for the dust and hot gases leaving the retort in the direction of the arrows G (FIGURE 2) the vertical and horizontal wall portions 62 and 64 are connected by an arcuate portion 63 which is on a radius of several inches and is closely spaced to the point where the inclined wall 60 and vertical wall 52 merge. The curved wall 63 causes the gas and dust to pass along a substantially curved path while the heavier particles are thrown by centrifugal force along a straight line path P indicated by the arrows in FIGURE 2. The heavier particles of aggregate material then fall by gravity along a vertical pathway P' and are returned along an inclined wall 65 as indicated by the arrows P" (FIGURE 2) where they are returned to the projecting end of the conveyor 74 to be thrown or projected into the retort along with the other aggregate particles conveyed to the dryer.

Thus, it will be seen that the various walls of the offtake housing 10 form a duct having a circular pathway arranged in a vertical plane with the horizontal wall portions 64-69 and 56 extending over the retort 6 and thereabove to the point 70 where it is then connected to the centrifugal separator 9 by the extension pipe 41. The success and thermal efiiciency of the invention is achieved by the arrangement of the wall portions of the ofi'take housing 10 with the conveyor projecting through the lower portion thereof and extending into substantially a position in which the plane of the wall 65 passes through substantially the major diametral portion of the head roller 73.

Operation In operation, it will be assumed that the oil burner 7 has been started and that the motors thereof (not shown) connected to a suitable source of electrical energy (not shown). As these motors are energized the retort 20 is rotated about its axis, the blower 44 is operated to create a reduced pressure or suction in the housing 37 of the centrifugal separator 9, and the motor 80 will operate the conveyor belt 74. With the motor 48 in operation the interior of the retort 20 is subjected to reduced pressure which causes the flame of the burner to travel a considerable distance into the retort.

In dryers of this type, sand, crushed stone and rocks are dried and occasionally several different types of sand are employed in the formation of asphalt and these are supplied by suitable conveying apparatus to the hopper 6 86.- Certain :particles of a size which will pass a 200 mesh screen, while the larger particles of aggregate material will be retained on a quarter inch screen and occasionally, certain particles will be retained on a screen having half inch interstices. The aggregate material to be dried is spread and fed to the hopper 86 where it is deposited upon the conveyor belt 74 and travels along the inclined conveyor belt surface 74 and is then projected over the moving end of the belt that travels over the roller 73 into the retort 20. As the material is deposited in the retort it is agitated and circulated by the flight bars 35. Thus, the aggregate material is carried upwardly and falls by gravity through the elongated flame passing through the retort and in so doing moisture and dust is removed therefrom. The ofltake gases and dust particles with certain entrained larger particles are conveyed into the oiftake housing 10-and' follow a circular :pathway indicated by the line of arrows G. The suction flow path carrying said particles is moving very rapidly since the air is traveling through the retort at approximately 45,000 cubic feet per minute. At this speed, or a slightly reduced one due to the increase in area of the housing 10 and its duct passage, the larger.

particles entrained in the stream of hot gases and dust are projected along a straight line path as indicated by the series vof arrows P. Upon striking the wall 67 the particles rebound thereon and fall by gravity along the pathway P and are returned to the forward end of the conveyor 74 as indicated by the arrows P".

With the ofltake housing constructed to form a vertical curved pathway forming a centrifugal flow path, considerable wear on the housing 10 is eliminated and a lange proportion of the aggregate particles are returned to the retort, thus eliminating Waste and the excessive Wear on various parts and wall portions of the ofl'take housing10 as well as the duct 56 and centrifugal separator 9. The

larger particles thus separated are always returned to the lower portion of the retort along with the initial stream which further reduces Wear at the intake end of the retort.

With the present construction a greater volume of aggregate material can be handled per time unit without increasing the dimensions of the retort and the aggregate material will be uniformly dried and heated to the proper temperature. It being appreciated that the larger particle sizes require a greater amount of time to be heated to the same temperature as the smaller ones such as those passing a 200 mesh screen. However, in the present invention larger particle sizes carried away with the hot are separated and returned to the retort for further heating and drying without requiring the use of an oir'take housing having a complex separator unit requiring a considerable number of moving parts and various expensive structures.

The form of the invention herewith shown and described is to be taken as a preferred embodiment thereof, and various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

What I claim is:

1. In a dryer for removing moisture from fine aggregate material, a rotary retort having charge and discharge ends, heating means at the charge end to create a flow of hot gases through said retort toward the charge end thereof, a vertical end Wall for the charge end having an opening, an enlarged conduit mounted in said opening inthe aggregate material are of eluding upper and lower portions, said lower portion being provided with inclined inner and outer walls extending upwardly and outwardly away trom said retort. said upper portion oflsaid conduit being provided with substantially vertical walls to form a substantially curved flow path for the hot gases emerging from said retort, the lower portion of said outer inclined wall being provided with an opening for receiving the material to be dried, whereby certain particles of material Will be projected out of said flow path and directed downwardly along the outer inclined wall toward the material being fed to the lower portion thereof.

2. In a dryer for removing moisture from fine aggregate material, a rotary retort having charge and discharge ends, heating means associated with the discharge end to create a flow of hot gases through said retort toward the charge end thereof, a vertical end wall for said charge end having an opening, a conduit having upper and lower portions, said lower portion being provided with inclined walls extending upwardly and outwardly from said retort, the walls of said lower portion being mounted in the opening of the vertical end wall, the upper portion of said conduit being provided with vertical wall portions mounted on the upper end of said lower portion to form a curved gas flow passage whereby dust and gas particles passing through said conduit will travel along a curved pathway so that the heavier particles will be thrown by centrifugal force against said inclined lower wall out of said pathway and will rebound and be returned to the charge end of said retort, along said lower inclined wall portion, one of said inclined walls being provided with an opening to receive material to be dried, and conveyor means for feeding material to said opening.

3. In a dryer for removing moisture from fine aggregate material, a rotary retort having charge and discharge ends, heating means at the discharge end to create a flow of hot gases through said retort toward the charge end, a vertical end wall for said charge end having an opening, a conduit having an enlarged portion at its lower end and a reduced portion at its upper end, said conduit having its lower enlarged end portion mounted in said opening and being adapted to conduct dust and hot gases from said retort, said enlarged lower portion including spaced upwardly and outwardly inclined wall portions forming the inner and outer walls of said conduit and the upper portion of said conduit being provided with substantially vertical walls extending upwardly from said lower enlarged conduit portion, said upper and lower portions of said conduit forming a substantially curved gas flow path for the discharge of products of combustion and for returning certain particles of material to said retort which have been thrown by centrifugal force from said gas flow path against said outer inclined wall, said outer inclined wall being provided with an opening for receiving the material, and a conveyor extending into said last named opening for feeding material to the lower portion of said inclined wall, said conveyor being located at the bottom portion of said outer inclined wall to receive some of said material which has been projected out of said flow path and return the same to said retort.

4. In a dryer for removing moisture from fine aggregate material, a rotary retort having charge and discharge ends, heating means at the discharge end for creating a flow of hot gases through said retort toward the charge end thereof, a conduit connected to the charge end for conducting the hot gases from said retort, said conduit being provided with an enlarged lower portion having upper and lower inclined walls arranged to extend ob liquely upward in a direction away from the lower portion of said retort for a portion of its length, a vertical conduit portion connected to the upper ends of said .inclined wall portions, a horizontal duct portion connected to the upper end of said vertical duct portion and arranged to extend above said dryer, said horizontal portion and vertical portion forming a sharp corner at the point of connection on one side of said conduit adjacent its upper end and a curved corner on the opposite side of said conduit adjacent its upper end whereby a circular gas flow path will be formed through said conduit and cause particles of material in said flow path to be projected by centrifugal force toward said corner portion and then returned to said charge end of the retort.

5. In a dryer for removing moisture from fine aggr gate material, a rotary retort having charge and discharge ends, heating means connected with the discharge end for creating a flow of hot gases through said retort toward the charge end, means for creating a reduced pressure in said retort, a conduit having one end connected to said retort and its opposite end connected to said reduced pressure creating means, said conduit being shaped to extend obliquely upward from said retort for a portion of its length and vertically for another portion of its length to terminate in a horizontal portion connecting said reduced presure creating means, said conduit being constructed and shaped to form a curved flow path whereby the hot gases and aggregate particles being carried away from the retort will travel along a curved passage with the heavier particles being thrown from said curved passage by centrifugal force and will rebound on one of said conduit walls and will be returned to said retort along an inclined wall of said oblique conduit portion, an endless conveyor having its discharge end projecting through an opening in the lower portion of said conduit for feeding material to the lower portion of the retort, adjustable sealing plates on said conduit adjacent said opening and rubber sealing flaps on said plates adapted to engage the load on the conveyor to seal the space between the load on said conveyor and the entrance opening thereof projecting through said inclined wall portion.

References Cited by the Examiner UNITED STATES PATENTS 1,123,877 1/1915 Behnke et a1 34-137 1,298,790 4/1919 Rich 34'242 X 1,704,482 3/1929 Lindsay 34-137 X 2,039,645 5/1936 Hechenbleikner 34137 X 2,313,956 3/1943 McGrane Ti l-57 2,705,133 3/1955 Barber et a1. 34135 2,755,513 .7/1956 Fleissner 3457 2,882,613 4/1959 Jacobson 34-137 2,959,869 11/1960 Ackerman 34135 VVILIJIAM F. ODEA, Primary Examiner.

NORMAN YUDKOFF, Examiner.

F. E. DRUMMO-ND, JOHN F. OCONNOR,

Assistant Examiners. 

1. IN A DRYER FOR REMOVING MOISTURE FROM FINE AGGREGATE MATERIAL, A ROTARY RESTORT HAVING CHARGE AND DISCHARGE ENDS, HEATING MEANS AT THE CHARGE END TO CREATE A FLOW OF HOT GASES THROUGH SAID RETORT TOWARD THE CHARGE END THEREOF, A VERTICAL END WALL FOR THE CHARGE END HAVING AN OPENING, AN ENLARGED CONDUIT MOUNTED IN SAID OPENING INCLUDING UPPER AND LOWER PORTIONS, SAID LOWER PORTION BEING PROVIDED WITH INCLINED INNER AND OUTER WALLS EXTENDING UPWARDLY AND OUTWARDLY AWAY FROM SAID RETORT, SAID UPPER PORTION OF SAID CONDUIT BEING PROVIDED WITH 